1. Field of the Invention
The invention relates to a vertically expandable enclosure which may be used for sleeping purposes, storage, etc., and which is adapted to be supported by the bed of a pickup truck or trailer.
2. Description of the Prior Art
The following U.S. Patents disclose different types of telescoping enclosures, some of which are adapted to be supported on the bed of a pickup truck or other type of vehicle.
______________________________________ 3,286,414 4,220,370 3,490,173 4,261,614 3,966,250 4,328,989 3,981,529 4,603,901 ______________________________________
All of the devices of these patents have one or more of the following problems:
1. They are cumbersome to set up for use and require much time and manual activation.
2. The mechanisms have exposed moving gears and parts which are dangerous to the operator/occupant.
3. Many use cables in the mechanism for driving or lifting the enclosures which stretch and need constant adjustment to provide level, safe lifting.
4. Some employ hydraulic cylinders which are expensive, require pumps and are subject to cold weather stalling and leakage.
5. The use of telescoping columns and jack screws that are subject to corrosion, sticking and binding.
6. A contractible door that has a very complex mechanism which requires many parts and is difficult to build and maintain.
7. None of the previous devices have seriously addressed the problems of aerodynamics of a moving unit or the use of structurally formed thermoplastics to obtain lighter weight and strength.